The present invention relates to a process for the automated growing of a group of plants and the corresponding installation.
Indeed, several growing methods exist among which may be distinguished the following essential types:
conventional growing in open fields,
growing in open ground or in pots but under shelter, and
soilless growing or growing in artificial soil under shelter.
Sub-classifications may in particular be distinguished in the last-mentioned method, depending on the temperatures and growing media.
Thus, in the soilless class under shelter, the growing media are varied and may be solid in the form of granulates: sand, gravel, expanded clay, pouzzolana, expanded glass balls, vermiculite, perlite, polystyrene, cork, etc. with a certain proportion of nutrient liquid solution with also liquids with no solid material.
In this particular case of growing, termed hydroponic culture, the growing in effect occurs with no granulate, the roots being directly plunged into this solution.
The advantages of the intensive growing under shelter are already known, and the advantages represented by soilless growing are also understood, but the same drawback remains in all cases: it is indeed necessary to plant the seeds or the young plants widely spaced apart so that at the moment of their maturity they are sufficiently spaced apart, and this requires a large surface area which is in use throughout the duration of the growing.
A partial remedy for such a problem consists in effecting successive sowings and planting outs, but in this case, the needs in labor are considerable, which cancels out some of the advantages that such a method might afford.
Growing processes have therefore been sought which permit a reduction in the planted areas. Thus, U.S. Pat. No. 4,166,341 relates to the individual growing of young plants in porous containers allowing the hydroponic growing thereof. These porous supports travel on mechanical conveyors in continuous U-shaped tunnels, the roots being permanently immersed in a nutrient solution.
While such a system is very perfected as concerns the growing conditions, it does not completely satisfy the desired objectives of reduction in the surface area used by an increase in this area in proportion to the evolution of the young plant and by an increase in the longitudinal and transverse distances. Indeed, the spacing of the young plants is not continuous but is effected in very few successive stages, which reduces the interest thereof and the container remains the same throughout the growth, which prevents any development unless the young plants are transferred to successive containers of larger size. The regulation of the longitudinal spacing of the young plants is possible by mechanically separating the containers, but in the transverse direction it will be understood that such a container cannot solve the problem unless the complete production line is shifted.
Austrian Pat. No. 250,093 discloses a process for growing in a container, but in which the growing medium is reduced in volume. Furthermore, the young plants are placed on suspended devices in which the young plants are superimposed so that the gain in the area is achieved in the direction of the height. To compensate for the small volume of the growing medium, the suspended devices are rendered mobile by mounting on a transfer installation of the type having a closed-loop cable which continuously rotates. At a point of the circuit, a tent with a nutrient solution nourishes the plants with a given periodicity and duration which is a function of the speed of the cable and the length of the container.
It will be understood that such a system remains complex, costly and does not solve the problem of a progressive and proportional increase in the cultivated surface as a function of the growth of the young plant.